When it comes to blogging and creating content for websites online, you need to optimize your images to keep from slowing down your site. If you have ever tested your website's speed or overall performance before, you probably saw that images make up for a large percentage of your load times.
My favorite free image optimizer is Web Resizer. With Web Resizer, you can quickly and easily optimize your images, reducing file size by as much as even 100 or 200% or even more. On top of that, you don't lose image quality and you get a lot of other useful features with this tool as well to help you crop, resize, optimize, add borders, change colors, etc.